Joe Jackson -- Someone Bailed Me Out Of Tax Debt!

Joe Jackson has a mysterious benefactor ... who just bailed him out of tax debt ... and we think we know who that person is.

Joe owed just over $70,000 in back California taxes ... way back, as in 1996.

Joe just didn't pay ... but suddenly -- 4 days ago -- the debt was cleared.

Joe doesn't have a lot of spare cash lying around these days, so who paid the dough? It's highly unlikely/out of the question that the Michael Jackson Estate anted up for Joe.

So the logical person is the one we're going with -- Katherine Jackson, who gets around $100K a month from the Estate. And even though Katherine and Joe don't live together, he has a lot of influence over her. And there's this ... his last known address is Katherine's house.

Educated guess, but we'd put money on it.